The present invention relates to a turbomachine stage, particularly a turbine or compressor stage of a gas turbine, with a housing, particularly a conical one, in which a moving vane arrangement with multiple moving vanes is arranged, which have an exterior shroud band with at least a radial sealing flange, as well as a method for determining a seal gap and/or an axial position of the moving vane arrangement of such a turbine machine stage.
By one or more radial sealing flanges arranged one after the other in an axial direction, the seal gap between a housing and an exterior shroud band can be reduced. In doing so, there may result, due to various operating conditions, light contact between the sealing flange and the housing, and consequently to abrasion on the sealing flange and/or a rubbing in the housing, so that the seal gap changes. Knowledge of the current seal gap can be advantageous, particularly to adapt the operation of the turbomachine to it and/or to perform or plan maintenance. Additionally or alternatively, knowledge of the current axial position of the moving vane arrangement can be advantageous, particularly to adapt the operation of the turbomachine to it.
An object of an embodiment of the present invention is to improve the maintenance and/or the operation of a turbomachine stage.
A turbomachine stage according to an aspect of the present invention may be in particular a turbine or compressor stage of a gas turbine, preferably of an aircraft engine.
It has a moving vane arrangement with multiple adjacent moving vanes in the peripheral direction, which can be constructed with a rotor of a turbomachine in a detachable or rigid manner, particularly in an integral manner. The moving vane arrangement is arranged in a housing, which in an embodiment—at least in the region of the moving vane arrangement—can converge or diverge in the flow direction, which is designated here for the purposes of a more concise overview in general as a conical housing. Similarly, the housing—at least in the region of the moving vane arrangement—may have in the flow direction an at least essentially constant cross-section, which is in this case correspondingly described as a cylindrical housing.
The moving vane arrangement has an exterior shroud band that may be formed by multiple exterior shroud band sections, to which one or more moving vanes may each be connected. In an embodiment, the exterior shroud band may converge or diverge in the flow direction or have an at least essentially constant exterior circumference, which in this case is correspondingly referred to as a conical or cylindrical exterior shroud band.
Radially outside on the exterior shroud band, there are arranged one or more radial sealing flanges spaced apart from each other in an axial or flow direction, which extend preferably radially outward in a strut-like manner as well as in the peripheral direction. Such radial sealing flanges are hereinafter referred to as sealing fin(s) for short.
According to an aspect of the present invention, the sole sealing flange-if there are multiple axially spaced-apart sealing flanges, then one or more-particularly all sealing flanges, each have a recess arrangement with one or more radial recesses. Several radial recesses may be distributed equidistantly or asymmetrically over the circumference. In an embodiment, the recess arrangement has exactly two, three, or four recesses. A recess may have in an embodiment two opposing flanks, which in a development, extend at least essentially in a radial direction and/or transition in an adjoining, preferably cylindrical ring-shaped exterior surface of the sealing flange, preferably in a curved structure. Between the flanks, there extends in a development a recess bottom, which in one embodiment may have at least essentially a cylindrical ring-shaped peripheral surface. Thus in an embodiment, a recess may be constructed particularly in a U-shaped manner.
In the recess, there is arranged a radial projection. In particular, it can extend radially outward from the recess bottom and in a development it can have at least essentially a cylindrical ring-shaped peripheral surface. When seen in a peripheral direction, the radial projection can be arranged in the recess, particularly in a centered manner, but similarly also in an off-centered manner. In an embodiment, the recess with the projection arranged in it is constructed symmetrically, which can advantageously generate identical signals in counter-directional rotations. Similarly, the recess with the projection arranged in it can also be constructed asymmetrically to advantageously generate different signals in counter-directional rotations.
On the housing, there is arranged a sensor arrangement with one or more capacitive sensors or probes for detecting a radial clearance to a peripheral surface of the sealing flange. Multiple sensors may be distributed equidistantly or asymmetrically across the circumference. In an embodiment, the sensor arrangement has exactly two, four or six sensors. In this case, a capacitive sensor for detecting a radial clearance to a peripheral surface of the sealing flange refers particularly to a means that delivers a signal, which depends on a radial distance of the sensor to the peripheral surface, preferably in a non-linear manner. In this case, a peripheral surface describes in particular a surface of a sealing flange, a recess, or a projection, which extends in the peripheral and axial direction, in other words the top side of the sealing flange, the recess, or the projection when seen from the outside.
When a sensor is passed over by a recess, the radial distance changes: first it increases as soon as the sensor detects the recess bottom. Then, the radial distance decreases when the sensor detects the projection. Then, it increases again as soon as the sensor detects the recess bottom on the opposite side of the projection going in the peripheral direction. Lastly, the radial distance decreases again to the initial value when the sensor detects the peripheral surface of the sealing flange next to the recess. Thus in an embodiment, when a recess rotates past a sensor, a general W-type signal trend results with four alternating, counter-directional signal swings. A signal swing refers in this case particularly to an increase or decrease, in particular an essentially plateau- or shoulder-shaped one, of the signal or the signal value of the sensor.
According to one aspect of the present invention, at least one signal swing of the sensor arrangement is detected as a result of at least one recess of the recess arrangement being detected by at least one sensor of the sensor arrangement. The subsequent detection or evaluation illustrated hereinafter by means of a recess and one or two sensors can be performed in an identical manner for multiple recesses and/or sensors, wherein then, in an embodiment, the detection results can be compared against each other, and in particular can be averaged.
A signal swing according to the invention can result, particularly when seen in the rotation direction, during a transition from a peripheral surface of the sealing flange next to a recess of the recess arrangement to this recess or (in the opposite direction thereto) from a recess of the recess arrangement to a peripheral surface of the sealing flange next to this recess. Both are equally referred to as signal swing as a result of detecting a recess by a sensor according to the present invention. Similarly, a signal swing according to the invention can also result when transitioning from a recess bottom of a recess of a recess arrangement to the projection of this recess or (in the opposite direction thereto) from a projection of a recess of the recess arrangement to a recess bottom of this recess next to this projection. This is also referred to as a signal swing as a result of detecting a recess by a sensor according to the present invention. In addition, such a signal swing can, or is, also be referred to as a signal swing as a result of detecting a recess and the projection in this recess by a sensor.
In an embodiment, the signal swing that results due to a change in distance between the recess bottom and the projection and/or between the projection and the recess bottom, i.e., a signal swing due to detecting a recess and the projection in this recess, is assigned to a radial distance of the moving vane arrangement on the basis of a prior calibration: for a capacitive sensor, the direct or indirectly detected capacity of a condenser changes as a result of the change of the effective peripheral surface of the recess bottom or projection. This change or this signal swing is different for different radial distances of the sealing flange to the sensor or the housing on which it is arranged. Accordingly, the signal swing can be assigned to a certain radial distance, wherein, in a prior calibration, certain signal swings were assigned according to certain radial distances. The assignment of a detected signal swing to a radial distance on the basis of a prior calibration can result in particular by means of a, preferably linear, interpolation or extrapolation between value pairs of the calibration.
In an embodiment, the sensor arrangement has at least two sensors, whose sensing surfaces form various, particularly counter-directional, preferably at least essentially equal angles to a rotational axis of the turbomachine stage. The angles are advantageously greater than 5° in size, particularly greater than 10°. Additionally or alternatively, in an embodiment, they are smaller than 75° in size, particularly smaller than 25°. In an embodiment, the angles are at least essentially equal ±15°, in another embodiment, at least essentially ±60°.
A sensor has in the peripheral direction a sensing region. The sensing regions lying one behind the other in an axial direction together form a sensing surface according to the present invention. A sensor has in particular a sensing surface that forms an angle to the rotational axis, where the sensor detects recesses or projections displaced in an axial direction before and after. The greater the size of the angle, the earlier or later the sensor detects two recesses or projections shifted in an axial direction or aligning with each other. If for example a sensor has a rectangular sensor surface facing the sealing flange, whose primary axis forms an angle to the rotational axis of the turbomachine stage, then the sensing surface also correspondingly forms this angle to the rotational axis.
By means of these sensing surfaces inclined against the rotational axis of the turbomachine, one can, according to an embodiment, detect an axial position of the moving vane arrangement. To this end in an embodiment, initially a signal swing of the sensor arrangement is detected as a result of a recess of the recess arrangement and/or the projection in this recess being detected by a sensor of the sensor arrangement. By the continued rotation of the rotor toward another sensor, another signal swing of the sensor arrangement is subsequently detected as a result of this recess and/or the projection in this recess being detected by another sensor of the sensor arrangement. The interval of these signal swings, particularly the time or rotational angle interval, can then be assigned, on the basis of a prior calibration, to an axial position of the moving vane arrangement. If the sensing surfaces of two sensors converge in an axial direction, the interval of the signal swings decreases as the sealing flange is displaced further in an axial direction. Reciprocally, the interval increases for sensing surfaces that are diverging in an axial direction or for a shift that is opposite the axial direction.
As explained precedingly, the intervals of signal swings of both sensors can be detected as a result of a transition from a peripheral surface of the sealing flange next to a recess to this recess, from a recess to a peripheral surface of the sealing flange next to this recess, from a recess bottom of a recess to the projection in this recess, and/or from a projection of a recess to a recess bottom of this recess next to this projection.
In addition or as an alternative to two sensors, whose sensing surfaces form various angles to the axis of rotation, the sensor arrangement in an embodiment can have at least one sensor, whose sensing surface converges or diverges in an axial direction. An axial position of the moving vane arrangement can also be detected by the following: given a sensor with a convergent sensing surface, the angle about which the sealing flange must be turned further until a recess or a projection is fully detected by the sensor or not at all detected by the sensor becomes smaller as the sealing flange is displaced further in an axial or convergence direction. Reciprocally, the angle about which the sealing flange must be turned further until a recess or a projection is fully detected by the sensor or not at all detected by the sensor increases the further the sealing flange is displaced in the divergence direction. A width of the corresponding signal swing or a shoulder of a sensor signal decreases or increases correspondingly with the axial position relative to the sensor with a convergent or divergent sensing surface. The width of a signal swing in this case refers in particular to a time or angle of twist across which the signal swing occurs. In an embodiment, this can be detected by the time or the angle between the falling below or exceeding specified limits by a sensor signal, but also by the time or the angle between sensor signals or sensor signal sequences with the same gradient, particularly half of a maximum gradient of the sensor signal or the sensor signal sequence.
Correspondingly, according to an embodiment of the present invention, at least one signal swing is detected after a recess of the recess arrangement is detected by a sensor, whose sensing surface converges or diverges in an axial direction, and a width of this signal swing is assigned to an axial position of the moving vane arrangement on the basis of a calibration.
As explained precedingly, in doing so, the width of a signal swing as a result of a transition from a peripheral surface of the sealing flange next to a recess to this recess, from a recess to a peripheral surface of the sealing flange next to this recess, from a recess bottom of a recess to the projection in this recess, and/or from a projection of a recess to a recess bottom of this recess next to this projection can be detected.
As explained precedingly, a signal swing results both for the signal between the recess bottom and projection or projection and recess bottom, and when entering or exiting a recess into or out of the sensing surface of a sensor. The signal swing is used in an embodiment of the present invention to detect abrasion of the sealing flange: the greater the abrasion, the smaller is the signal swing. Accordingly, in an embodiment, at least one signal swing of the sensor arrangement can be detected as a result of a recess of the recess arrangement and a sealing flange peripheral surface adjoining this recess, particularly positioned before or after in a rotational direction, being detected by a sensor of the sensor arrangement and this signal swing can be assigned to an abrasion of the sealing flange on the basis of a prior calibration.
The seal gap between the sealing flange and the housing, particularly an inlet coating of the housing, can depend on a rubbing on the housing and/or the axial position of the sealing flange, in addition to the radial distance of the sealing flange to a housing-affixed sensor and a possible abrasion of the sealing flange. Accordingly in an embodiment of the present invention, a rubbing of the housing opposite the sealing flange, particularly of a housing inlet coating opposite the sealing flange, is detected, particularly in a periodic manner. When detecting the seal gap, this inlet coating can be taken into account, and in particular be added to a detected radial distance and/or abrasion of the sealing flange.
As explained precedingly, the signal swings or their intervals can be assigned to radial clearances or axial positions by preferably two-dimensional calibration. Accordingly, in an embodiment of the present invention, in particular initially, from the intervals between signal swings, which by means of sensors with counter-directionally inclined sensing surfaces detect one after the other the same recess, and/or from the width of a signal swing that is detected by a sensor with an axially converging or diverging sensing surface, an axial position of a sealing flange is determined and, in particular subsequently, from the signal swings between the recess bottom and projection or adjoining, not recessed, peripheral surface of the sealing flange, the radial distance or abrasion of the sealing flange is determined on the basis of the two-dimensional calibration. In an embodiment, a two-dimensional calibration is used to assign each pair of axial positions and radial distances or seal gaps to an interval between signal swings of sensors, whose sensing surfaces form various angles, or a width of a signal swing of a sensor with axially converging or diverging sensing surfaces, and additionally a signal swing, particularly as a result of detecting a recess and its projection. In this way, when detecting the distance or width and signal swing on the basis of a calibration, the axial position and radial distance or seal gap can be determined. In a development, a current seal gap can be determined from this together with the also detected rubbing.
In an embodiment of the present invention, a peripheral surface of the radial projection is radially depressed in the recess. A rubbing of the sealing flange's remaining peripheral surface surrounding the recess hereby also does not change the signal swing between the recess bottom and projection.
A recess can be arranged entirely in an exterior shroud band section. Similarly, a recess, particularly the projection, can be jointly constructed by means of two adjacent exterior shroud band sections or the recess, particularly the projection, can extend across the contact surface of two adjacent moving vanes. In doing so, the recess, particularly the projection, can be symmetrically distributed on both adjacent exterior shroud band sections or extend symmetrically to the contact surface.
In an embodiment, the sealing flange of one or two adjacent exterior shroud band sections is radially depressed in relation to the sealing flange of the other exterior shroud band sections connecting to it or them, so that the recess extends across one or two entire exterior shroud band section(s). In this way, a recess with a radial projection can be constituted in a particularly simple way. The radial projection can be arranged on the mutually facing contact surfaces of these adjoining exterior shroud band sections.
In an embodiment, the turbomachine stage has a processing means that is configured to execute a method described here. A means according to the present invention may be constructed with hardware and/or software technology, and particularly have a, data- or signal-related, particularly digital, processing, particularly microprocessor unit (CPU), preferably with a storage and/or bus system, and or one or more programs or program modules. The CPU can be designed to execute commands that are implemented as a program stored in a storage system, detect input signals from a data bus and/or deliver output signals to a data bus. A storage system may have one or more, particularly various, storage media, particularly optical, magnetic, solid-body, and/or other non-volatile media. The program can be constituted in such a manner that it can incorporate or execute the methods described here and thereby detect in particular a seal gap and/or an axial position.
Additional advantageous developments of the present invention emerge from the following description. The drawings are partially schematized.